Many devices that are powered through electrical current operate using either direct current (DC) or alternating current (AC) power. Various devices convert AC current from an electrical power source to DC current, and convert DC current to AC current. Electrical inverters are one example of devices that generate an AC output power signal using a DC input signal as a source. In two common configurations, an inverter generates an AC signal with a sinusoidal waveform having an output voltage of approximately 120 volts and a frequency of 60 Hz to conform with power grids in the United States and other countries, or with an output voltage of approximately 240 V and a frequency of 50 Hz to conform to power grids in Europe and Asia.
In a typical inverter design, four transistors are switched at high-speed to generate a sinusoidal AC waveform from an input DC waveform. The transistors switch on and off repeatedly to invert the DC signal source between positive and negative voltage values so that the output signal approximates an AC sinusoidal signal. Typically, the high-frequency switching transistors switch on and off at a much higher frequency than the frequency of the AC output signal. A portion of the input energy from the DC signal source is lost each time one of the four transistors switches between an on and an off state. The switching loss due to the switching transistors increases as the desired frequency of the AC output signal increases because the transistors switch at a higher frequency to generate the AC signal. Additionally, existing inverters are typically configured to accept power from a stable DC power source that does not vary substantially over time and to provide the AC power output to a load with a substantially constant resistance. If either the DC power input or load output resistance varies during operation, existing inverters may become unstable and produce output power signals that deviate from the desired AC output waveform. Consequently, improvements to DC to AC inverters that operate more efficiently and provide stable AC power signals would be beneficial.